In recent years, magnetic recording media having high coercive force as metal tapes and barium-ferrite (Ba-ferrite) tapes, etc. have been developed for magnetic tape recorders/reproducers in response to demands for high density recording. However, such magnetic recording media with such a high coercive force have a relatively small saturation magnetic flux density. If such magnetic recording media are used with a conventional ferrite head, an undesired magnetic saturation occurs in the vicinity of the magnetic gap due to the small saturation magnetic flux density.
To overcome the problem, a head whose magnetic gap is composed of a metal magnetic substance has been adopted. This metal magnetic substance has extremely less specific resistance than conventional Mn-Zn ferrite. Also the practical permeability of the metal magnetic substance is relatively low, in the order of several MHz frequency band, due to the skin effect of eddy-current loss. For those reasons, a laminated core head which obtains the main core by laminating metal magnetic film and non-magnetic film alternately by the thin film forming technology has come to be employed.
Shown in FIG. 1 is a plan showing a conventional laminated core type magnetic head.
The laminated core head 1 is composed of the laminated cores 2 and 3. These laminated cores 2 and 3 are produced by laminating the metal magnetic film 5 and the insulation film (Sio2, Al203) 6 alternately on the non-magnetic insulating plate 4 by the sputtering method or the evaporation method and further, by laminating non-magnetic insulating plate 8 by glass fusing with the glass 7. The metal magnetic film 5 and the insulating film 6 are formed in thickness of the track width (Tw) and construct the magnetic gap section 9. The magnetic gap is left by the sputtering of film 10 which is made of SiO2, etc. in specified thickness and inserted into the magnetic gap between the laminated cores 2 and 3.
The laminated core head 1 is able to generate a more strong recording magnetic field than a ferrite head because it uses the metal magnetic film 5 which has a high flux density and has a satisfactory write capability for such recording media having a high coercive force as metal tape, etc. (coercive force.gtoreq.1500 e). Further, as the laminated core head 1 is a laminated structure provided with the insulation layer 6 between the metal magnetic films 5, eddy-current loss by a metal magnetic film having good conductivity is reduced.
However, the laminated core head 1 has a defect in that the recording reproduction efficiency is not good as all magnetic paths are formed in the same width as the recording width (the track width Tw).
As a solution against this defect, a composite head shown in FIG. 2 is considered.
The gapping core 11 and the looping core 12 are formed individually. The gapping core 11 is made of a metal magnetic substance and the looping core 12 is made of such oxide magnetic substance as ferrite having satisfactory high frequency characteristics. Since the gapping core 11 is made of metal magnetic substance, generation of magnetic saturation in the vicinity of the magnetic gap 13 can be prevented and a high recording magnetic field strength is obtainable.
However, it is extremely difficult to get magnetic continuity on the joining surface between the gapping core 11 and the looping core 12. In addition, there was a problem that high manufacturing technology and a number of manufacturing processes were required.
Thus, the conventional magnetic head described above had such problems that in case of the laminated core head, all magnetic paths are formed in the same width as the track width and recording reproduction efficiency is not good and in case of the composite head, no magnetic continuity is obtainable on the joining surface between the gapping core and the looping core.